Preparation, Characterization And Application Of Molecularly Imprinted Polymers Toward Key Veterinary Drugs Of Erythromycin And Chlorpromazine In Food Safety Detection

The development of new methods and new materials to enhance the effect of sample preparation has become the hotspot of food safety analysis.For its outstanding advantages, such as predetermined recognition ability, relative ease and low cost of preparation, and potential application to a wide range of target molecules, molecularly imprinted solid phase extraction based on molecularly imprinted polymers has attracted much attention.In this thesis, the principle, methodology, history and application of molecularly imprinted technology were thoroughly reviewed. The development and application of molecularly imprinted technology in food safety were also comprehensively introduced. Basis on this, the molecularly imprinted polymers of erythromycin and chlorpromazine were prepared by non-covalent methods. Then, the recognition characteristics and binding mechanism of these polymers were discussed and the applications of polymers as solid phase extraction sorbents for erythromycin and chlorpromazine pre-treatment were finally investigated. The main results of these studies are as follows: Six of erythromycin (ERY) imprinted polymers and non-imprinted polymers were prepared by bulk polymerization. Base on binding analysis, the MIP11 with better binding property were selected for subsequent research. The optimized system was with 1:2 ratio of template to MAA, EGDMA as the cross-linker and mixture of methanol/ acetonitrile (2:3, v/v) as the porogen. Furthermore, the physical profile of MIP11 was characterized by SEM, BET analysis, TGA, UV-vis and FT-IR spectroscopy analysis. The imprinted mechanism and recognition ability of the polymer were studied by adsorption experiments and chromatographic methods. The equilibrium binding experiments showed that the binding sites of MIPs were heterogeneous with two binding sites. For high affinity binding sites, Bmax1=12.30 mg g-1, for low affinity binding sites, Bmax2=72.09 mg g-1.In this study, the performance of the MIP11 as solid-phase extraction (SPE) sorbents was evaluated. After optimization, the recoveries of ERY by molecularly imprinted solid phase extraction (MISPE) could come to 80%, when using 40% methanol as loading buffer, 80% methanol as washing solvent and 80% methanol in PBS as the elute buffer to disturb the interaction between MISPE column and ERY. As control, the recoveries of non-imprinted solid phase extraction (NISPE) were less than 30%. Selectivity analysis showed that MIP11 could recognize ERY with moderate cross-reactivity for other macrolides. And molecular size and shape had served as the main factors for the specific affinity of the synthesized MIP11. When the MISPE column was used to extract ERY from pig muscle, the matrices influence towards the analysis was obviously reduced and the sensitivity of HPLC-UV was highly enhanced. At 3 spiked levels, all the recoveries of ERY were more than 79%. The performance of MISPE toward the spiked tap water further showed the high pre-concentration capability of the ERY imprinted polymers. In this study, the chlorpromazine molecularly imprinted polymers were also prepared, and the synthetic method and system composition toward the selective capability of the synthesized polymers were investigated firstly. The result showed that the polymer prepared by bulk polymerization had the highest selectivity when using MAA as the monomer, TRIM as the cross-linker, and with 1:4 ratio of template to momomer. By HPLC, FT-IR, BET and SEM analysis, the self-assemble process between chlorpromazine and functional monomer was studied. Adsorption selectivity and capability analysis indicated the MIP with relative high specificity. The maximum specific adsorption capability of MIP was 10mg mL-1. When using MIP as MISPE sorbents, the cartridge showed better concentration and purification effect than commercial C18 column.